STUDIES ON CHEMICALLY DEPOSITED FILMS OF BISMUTH–SULFIDE (Bi2S3)

The chemical method for deposition of bismuth–sulfide (Bi2S3) thin films is pre-sented. For the deposition, the triethanolamine complex of bismuth nitrate was allowed to react with aqueous thiourea solution. Good quality (very uniform, re-producible, tightly adherent, specularly reflecting and crack free) deposits are ob-tained. Micro–structural characterizations were carried out by X–ray diffraction (XRD) and scanning electron microscope (SEM) in order to study the crystallinity and the surface topography of the films. The studies establish that bismuth–sulfide thin films become weak crystalline phase upon annealing in air near 393 K and remain stable up to 573 K. The SEM photographs reveal that crystal size and perfection increase when increasing the thickness of the film. The thermal stabil-ity of the powder samples was studied also, using a Shimadzu DSC–50 scanning calorimeter. From the electrical measurements, an activation energy of 0.155 eV was obtained in the temperature range of 300 K to 363 K. The conduction above 363 K was found to be intrinsic with a band–gap of 1.38 eV. 1